Sudden Death Syndrome

Source: Don Hershman, University of Kentucky

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Fusarium virguliforme
(formerly Fusarium solani f.sp. glycines)
Sudden death syndrome is a soilborne disease of economic concern in soybean production areas of NY. Though it has only been confirmed in a handful of counties in NY, it is likely more widespread. As with most of the soilborne diseases, occurrences of sudden death syndrome depend on favorable conditions, including a cool, wet spring, followed by a hot, dry summer. Infection occurs as early as seed germination and seedling emergence, but symptoms usually do not appear until flowering and later reproductive stages. Symptoms often first appear as bright yellow flecks on the leaves or interveinal chlorosis, similar to that of brown stem rot and northern stem canker. The interveinal chlorosis may expand, leaving only green veins on the leaves. Chlorotic leaf tissue eventually becomes necrotic, and unlike brown stem rot and northern stem canker, the dead leaflets will detach from the petioles and fall to the ground, leaving petioles attached to the stems. Young leaves emerging in the upper canopy as symptoms begin to develop may be cupped or distorted and chlorotic. The fungus diminishes the root mass, and the xylem of the tap root and lower stem may be discolored, while the pith remains white. Infection may result in pod abortion or reduced seed size and may have a large impact on yield in a severe epidemic. Reducing soil compaction, planting early maturing varieties, crop rotation and seed treatments applied to high quality seed are good management practices for minimizing losses to sudden death syndrome.